Langmuir-blodgett monolayer masked chemical etching: An approach to broadband antireflective surfaces

We report a simple bottom-up approach for the fabrication of highly antireflective optical surfaces. The Langmuir-Blodgett (LB) monolayer with domain structures was used as a mask for selective etching of Si in a KOH solution. The obtained pyramidal structures can reduce the reflectivity to less than 6% at the wavelengths from 400 to 2400 nm. This technique combines the simplicity and scalability of self-assembly and cost benefits of chemical etching. These antireflective structures may have potential applications in optical devices and solar cells. Moreover, the reflectivity of polymer materials can also be reduced by transferring the pyramidal structures onto their surfaces via molding and nanoimprint lithography (NIL).